I did! I got a new Torker LX Unistar for my birthday.(it’s tomorrow!) 
I’m turning 12! It had an extended seatpost and we had to cut it down. 
Now I HAVE to be wearing my shoes when riding…And it’s painted, so it won’t get rusty.
Uhm… i think you need of PC cooling advice here… aluminium heatsinks are used, because aluminium is one of the best materials for CONDUCTING heat. (copper is even better and used alot in PC heatsinks, gold is also better… but its gold…)
The point of a heatsink, is to dissipate the heat over a very large surface area, and then blow it away with a fan (usually). Steel does not conduct heat very well… (although it will get hot if you weld it…) A PC processor will be less than 100W a soldering iron… well unless its a electronics 25W one… is like LOADS more.
DOnt take it as an insult, i dont mean to be nasty in any ways… just trying to explain…
Rusty
Try the non-hazardous rust remover from D-Rust-It (d-rust-it.com) It works wonders without any work… When your done, just pour it down the drain.
Good luck